M.Sc Thesis


M.Sc StudentBegun Benyamin
SubjectPerformance Study of Low-Cost Rocket Controlled by
Solenoid
DepartmentDepartment of Aerospace Engineering
Supervisor PROFESSOR EMERITUS Shaul Gutman
Full Thesis textFull thesis text - English Version


Abstract

Currently, among aerospace industries, there is an increasing demand for advancements in rocket precision using control systems. Although these systems have provided significant technological advancement in this arena, they are accompanied by high costs and complex mechanisms. Previous projects have addressed precision munitions; however, the challenges of obtaining the balance of affordability with performance have not been confronted.

Cost is a major driving factor in the development and production of precision systems. Expensive, high-performance actuators cannot be used on low-cost systems. These aspects result in the increasing technical difficulty for low-cost precision projectiles.


With the development of technology, the servo system has become a widely utilized control system. Despite its common usage, the mechanical complexity and high costs are of disadvantage to aerospace industries.


As a result of the challenges associated with the servo system, a considerable amount of research has been devoted to obtaining an alternative solution. A credible solution is the solenoid actuator, which offers advantages such as low-cost and high power-to-weight ratio.


Although the solenoid actuator offers a high power-to-weight ratio, this actuating system, just like other actuating systems that supposed to be installed inside a guidance kit, has volume limitations. Due to these limitations, one of the main challenges to the guidance kit designer is to be able to place such actuators that will manage to supply the required forces.


To be able to place small actuators inside the guidance kit, it is required to use a guidance law which will require small maneuver capabilities while still achieving small miss distances.

Currently, many different guidance laws offer good performances concerning miss distance, however, the maneuver capabilities that they require are relatively high, and therefore, it is nearly impossible to place small actuators in the guidance kit.


Much researches were conducted to develop a guidance law that will result in small miss distances while requiring low control accelerations. One of the guidance laws that were studied is the Predictor-Corrector law, which utilized in many guidance systems. Although this guidance law is popular in many modern ammunitions, it has its disadvantages, such as on-board processing. Another guidance law that was studied recently is MVG law, which is developed from the basics of Vector Guidance law. Unlike Vector Guidance, MVG took into account relative accelerations such a drag and gravity to make it more accurate for endo-atmospheric scenarios. Even though this guidance law resulted in low control efforts, it did not promise an accurate hit. Large miss distances occurred when the guidance law did not have a solution to its Time-to-go equation, which is affected by the additional drag force terms.


Achieving affordability goals while still meeting performance objectives is a non-trivial task. The research will introduce a unique guidance law that will reduce the actuating needs while simultaneously enable precision targeting. This result is obtained by suggesting a new method to calculate the Time-to-go equation in such a way that will guarantee small miss distances while keeping the acceleration commands low.